1. Field of the Invention
The present invention relates to technique concerning a data processing device, an encryption communication method, a key generation method and computer program for executing these methods.
2. Related Background Art
Recently, a network security function has come to be requested to a data processing device. To comply with such a request, for example, the data processing device as disclosed in Japanese Patent Application Laid-Open No. 2002-259108 has and holds a public key certificate and a private key (here, a secret key which corresponds to a public key is called “a private key”) corresponding thereto, and executes authentication based on the public key certificate in accordance with a request from a document server or a client computer.
Incidentally, it is assumed that a pair of an encryption public key (i.e., public key for encryption) and a decryption private key (i.e., private key for decryption) is created outside the data processing device, a certificate of the created pair is issued from a reliable organization, and the issued certificate is installed in the data processing device. Here, the pair of the encryption public key and the decryption private key is called “encryption key/private key pair” or “private key/encryption key pair” hereinafter. In such a circumstance, with respect to the data processing device which does not have an input unit such as an FD (floppy™ disk or flexible disk), a CD (compact disk) or the like, it is necessary to install through a network the private key/public key pair and the certificate from a terminal located on the relevant network to the data processing device.
Moreover, to safely install the private key/public key pair and the certificate thereof from the terminal to the data processing device through the network, it is desirable to execute cryptographic communication (or cipher communication) between the terminal and the data processing device. In this connection, a private key/public key pair is necessary to execute the cryptographic communication.
However, there is a possibility that the data processing device in a factory shipment status does not have own public key/private key pair. In such a case, the cryptographic communication for installing the private key/public key pair and the certificate thereof might not be able to be executed.
Moreover, for example, in an environment that takes not much interest in security or in an environment that does not necessarily need perfect security, all users do not necessarily indicate generation of the public key and the private key before executing the cryptographic communication.
For this reason, even if the user does not execute a complicated operation to generate the public key and the private key, it is desirable to appropriately prepare and provide the public key/private key pair.
Moreover, even after the public key/private key pair was once prepared, if the public key/private key pair is damaged, it is desirable to newly prepare and provide the public key/private key pair without any complicated operation by the user.